Add CI workflow for testing code

Author: AndrewSazonov

.github/workflows/ci-testing.yaml

@@ -0,0 +1,53 @@
+name: Test code
+
+on:
+  # Trigger the workflow on push
+  push:
+    # Every branch
+    branches:
+      - '**'
+    # But do not run this workflow on creating a new tag starting with 'v', e.g. 'v1.0.3' (see pypi-publish.yml)
+    tags-ignore:
+      - 'v*'
+  # Trigger the workflow on pull request
+  pull_request:
+    branches:
+      - '**'
+  # Allows you to run this workflow manually from the Actions tab
+  workflow_dispatch:
+
+# Allow only one concurrent workflow, skipping runs queued between the run in-progress and latest queued.
+# And cancel in-progress runs.
+concurrency:
+  group:
+    ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  test-code:
+
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-24.04, windows-2022, macos-13, macos-14]
+        python-version: ['3.12']
+
+    runs-on: ${{ matrix.os }}
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Upgrade package installer for Python
+        run: python -m pip install --upgrade pip
+
+      - name: Install Python dependencies
+        run: python -m pip install -r requirements.txt
+
+      - name: Run Python tests
+        run: PYTHONPATH=$(pwd)/src python -m pytest tests/ --color=yes